The Gentiles heard and believed the word.
The Gentiles were saved, baptised in the Holy Ghost and spoke in tongues, But they weren't baptised in water, Proving that water baptism doesn't save.
Here is more proof that water baptism doesn't save, Purify or cleanse.
Acts 15: 7--9.
V7, The Gentiles heard the gospel, And believed it.
V8, God gave them the Holy Ghost, See Acts 10: 44.
V9They were purified by faith.
Please note, No mention of water baptism.
Please note, This was all done before they were baptised in water.
The Bible rests it's case.
The point is, can one be saved who never heard the gospel? No, therefore preaching saves for it is how the gospel that saves is spread.
Water baptism remits sins, Acts 2:38, baptism with the Holy Spirit does NOT save/remit sins, so Cornelius was lost in his sins until he obeyed the command to be water baptized. Baptism with the Holy Spirit had nothing to do with his personal salvation.
--God sent an angel to Cornelius telling Cornelius to send for Peter
--God gave Peter a vision that Gentiles were 'clean'
--God baptized Gentiles with the Holy Ghost
When Peter told the Jews about these actions of God, the Jews "held their peace, and glorified God, saying, Then hath God also to the Gentiles granted repentance unto life." Acts 11:18. So the purpose of these actions by God was to prove to the Jews salvation was not just for the Jews, but is also meant for the Gentiles. So baptism with the HG had nothing to do with Cornelius' personal salvation but was a means God used to show the Jews salvation is to go to the Gentiles.
Preaching saves for Cornelius would be saved by "words" Acts 11:14, and the HG fell upon Cornelius just as Peter began to speak those saving "words" of the gospel, so Cornelius did not know the gospel message when the HG fell upon him.